1. Field of Endeavor
The present disclosure relates to an apparatus and method for controlling medium voltage inverter.
2. Background
This section provides background information related to the present disclosure which is not necessarily prior art.
In general, equipment referred to as a power converter, inverter or drive is employed to provide power to another piece of equipment such as a motor. Specifically, such an inverter (inverter is used generally herein to refer to inverters, converters, drives) is coupled to a utility connection to receive incoming input power such as a three-phase AC (Alternating Current) power. The inverter conditions the power to provide a conditioned power signal to the equipment to be powered. In this way, incoming power to the equipment may be of improved efficiency, leading to reduced costs to operate the equipment.
However, in a case a commercial AC power is employed for direct use to a medium voltage inverter in industrial fields, a frequency is generally fixed to 60 Hz to hardly save energy. Recently, energy-saving becomes a big issue to contribute to an increased use of medium voltage inverter.
The medium voltage inverter drives a motor using a high voltage such as 3.3 kV, 6.6 kV, or 10 kV, and generally is used to drive an industrial load of large inertia. For a non-limiting example, the medium voltage inverter is widely used to drive loads such as important fans and pumps. In case of a load being a motor rotating a fan, a medium voltage inverter controls a rotation speed of the motor to adjust a wind amount, whereby an optimum energy saving can be realized.
In a case an instantaneous power interrupt is generated by issues such as weather changes and power supply in driving an inertially large load such as a fan or a pump, the medium voltage inverter may generate errors such as trip and the like. Approximately five times of instantaneous power interrupts reportedly occur a year. A fatal failure may be inflicted on essential load facilities if no preventive measure is made to the instantaneous power interrupts, and may create a major problem bringing about defects to products and/or personal injury.
Thus, there is a need to safely drive a motor lest the medium voltage inverter should be generated with a trip, in a case an instantaneous power interrupt occurs.